Network Formation: R&D Cooperation Propensity and Timing Among German Laser Source Manufacturers
Muhamed Kudic, Andreas Pyka, Marco Sunder
IWH Discussion Papers,
No. 9,
2013
Abstract
Empirical evidence on the evolution of innovation networks within high-tech industries is still scant. We investigate network formation processes by analyzing the timing of firms to enter R&D cooperations, using data on laser source manufacturers in Germany, 1990-2010. Network measures are constructed from a unique industry database that allows us to track both the formation and the termination of ties. Regression results reveal that a firm's knowledge endowment (and cooperation experience) shortens the duration to first (and consecutive) cooperation events. The previous occupation of strategic network positions is closely related to the establishment of further R&D cooperations at a swift pace. Geographic co-location produces mixed results in our analysis.
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Human Capital and Fertility in Germany after 1990: Evidence from a Multi-Spell Model
Marco Sunder
IWH Discussion Papers,
No. 22,
2009
Abstract
We analyze the timing of birth of the first three children based on German panel
data (GSOEP) within a hazard rate framework. A random effects estimator is
used to accommodate correlation across spells. We consider the role of human
capital – approximated by a Mincer-type regression – and its gender-specific
effects on postponement of parenthood and possible recuperation at higherorder
births. An advantage of the use of panel data in this context consists in
its prospective nature, so that determinants of fertility can be measured when
at risk rather than ex-post, thus helping to reduce the risk of reverse causality.
The analysis finds evidence for strong recuperation effects, i.e., women with
greater human capital endowments follow, on average, a different birth history
trajectory, but with negligible curtailment of completed fertility.
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